diff --git a/wp-admin/includes/update-core.php b/wp-admin/includes/update-core.php
index 60b0b8862e..868adc4900 100644
--- a/wp-admin/includes/update-core.php
+++ b/wp-admin/includes/update-core.php
@@ -1,7 +1,125 @@
 <?php
 
+global $_old_files;
+
+$_old_files = array(
+'wp-admin/bookmarklet.php',
+'wp-admin/css/upload.css',
+'wp-admin/images/box-bg-left.gif',
+'wp-admin/images/box-bg-right.gif',
+'wp-admin/images/box-bg.gif',
+'wp-admin/images/box-butt-left.gif',
+'wp-admin/images/box-butt-right.gif',
+'wp-admin/images/box-butt.gif',
+'wp-admin/images/box-head-left.gif',
+'wp-admin/images/box-head-right.gif',
+'wp-admin/images/box-head.gif',
+'wp-admin/images/heading-bg.gif',
+'wp-admin/images/login-bkg-bottom.gif',
+'wp-admin/images/login-bkg-tile.gif',
+'wp-admin/images/notice.gif',
+'wp-admin/images/toggle.gif',
+'wp-admin/includes/upload.php',
+'wp-admin/js/dbx-admin-key.js',
+'wp-admin/js/link-cat.js',
+'wp-admin/profile-update.php',
+'wp-admin/templates.php',
+'wp-includes/js/dbx.js',
+'wp-includes/js/fat.js',
+'wp-includes/js/list-manipulation.js',
+'wp-includes/js/jquery/jquery.dimensions.min.js',
+'wp-includes/js/tinymce/langs/en.js',
+'wp-includes/js/tinymce/plugins/autosave/editor_plugin_src.js',
+'wp-includes/js/tinymce/plugins/autosave/langs',
+'wp-includes/js/tinymce/plugins/directionality/images',
+'wp-includes/js/tinymce/plugins/directionality/langs',
+'wp-includes/js/tinymce/plugins/inlinepopups/css',
+'wp-includes/js/tinymce/plugins/inlinepopups/images',
+'wp-includes/js/tinymce/plugins/inlinepopups/jscripts',
+'wp-includes/js/tinymce/plugins/paste/images',
+'wp-includes/js/tinymce/plugins/paste/jscripts',
+'wp-includes/js/tinymce/plugins/paste/langs',
+'wp-includes/js/tinymce/plugins/spellchecker/classes/HttpClient.class.php',
+'wp-includes/js/tinymce/plugins/spellchecker/classes/TinyGoogleSpell.class.php',
+'wp-includes/js/tinymce/plugins/spellchecker/classes/TinyPspell.class.php',
+'wp-includes/js/tinymce/plugins/spellchecker/classes/TinyPspellShell.class.php',
+'wp-includes/js/tinymce/plugins/spellchecker/css/spellchecker.css',
+'wp-includes/js/tinymce/plugins/spellchecker/images',
+'wp-includes/js/tinymce/plugins/spellchecker/langs',
+'wp-includes/js/tinymce/plugins/spellchecker/tinyspell.php',
+'wp-includes/js/tinymce/plugins/wordpress/images',
+'wp-includes/js/tinymce/plugins/wordpress/langs',
+'wp-includes/js/tinymce/plugins/wordpress/popups.css',
+'wp-includes/js/tinymce/plugins/wordpress/wordpress.css',
+'wp-includes/js/tinymce/plugins/wphelp',
+'wp-includes/js/tinymce/themes/advanced/css',
+'wp-includes/js/tinymce/themes/advanced/images',
+'wp-includes/js/tinymce/themes/advanced/jscripts',
+'wp-includes/js/tinymce/themes/advanced/langs',
+'wp-includes/js/tinymce/tiny_mce_gzip.php',
+'wp-includes/js/wp-ajax.js',
+'wp-admin/admin-db.php',
+'wp-admin/cat.js',
+'wp-admin/categories.js',
+'wp-admin/custom-fields.js',
+'wp-admin/dbx-admin-key.js',
+'wp-admin/edit-comments.js',
+'wp-admin/install-rtl.css',
+'wp-admin/install.css',
+'wp-admin/upgrade-schema.php',
+'wp-admin/upload-functions.php',
+'wp-admin/upload-rtl.css',
+'wp-admin/upload.css',
+'wp-admin/upload.js',
+'wp-admin/users.js',
+'wp-admin/widgets-rtl.css',
+'wp-admin/widgets.css',
+'wp-admin/xfn.js',
+'wp-includes/js/tinymce/license.html',
+'wp-admin/cat-js.php',
+'wp-admin/edit-form-ajax-cat.php',
+'wp-admin/execute-pings.php',
+'wp-admin/import/b2.php',
+'wp-admin/inline-uploading.php',
+'wp-admin/link-categories.php',
+'wp-admin/list-manipulation.js',
+'wp-admin/list-manipulation.php',
+'wp-includes/comment-functions.php',
+'wp-includes/feed-functions.php',
+'wp-includes/functions-compat.php',
+'wp-includes/functions-formatting.php',
+'wp-includes/functions-post.php',
+'wp-includes/js/dbx-key.js',
+'wp-includes/js/tinymce/plugins/autosave/langs/cs.js',
+'wp-includes/js/tinymce/plugins/autosave/langs/sv.js',
+'wp-includes/js/tinymce/themes/advanced/editor_template_src.js',
+'wp-includes/links.php',
+'wp-includes/pluggable-functions.php',
+'wp-includes/template-functions-author.php',
+'wp-includes/template-functions-category.php',
+'wp-includes/template-functions-general.php',
+'wp-includes/template-functions-links.php',
+'wp-includes/template-functions-post.php',
+'wp-includes/wp-l10n.php',
+'wp-admin/import-b2.php',
+'wp-admin/import-blogger.php',
+'wp-admin/import-greymatter.php',
+'wp-admin/import-livejournal.php',
+'wp-admin/import-mt.php',
+'wp-admin/import-rss.php',
+'wp-admin/import-textpattern.php',
+'wp-admin/quicktags.js',
+'wp-admin/upload.php',
+'wp-images',
+'wp.php',
+'wp-content/themes/default/attachment.php',
+'wp-content/themes/default/images/kubrickbg.jpg',
+'wp-content/plugins/markdown.php',
+'wp-content/plugins/textile1.php',
+);
+
 function update_core($from, $to) {
-	global $wp_filesystem;
+	global $wp_filesystem, $_old_files;
 
 	// Sanity check the unzipped distribution
 	apply_filters('update_feedback', __('Verifying the unpacked files'));
@@ -43,6 +161,14 @@ function update_core($from, $to) {
 	// Remove maintenance file, we're done.
 	$wp_filesystem->delete($maintenance_file);
 
+	// Remove old files
+	foreach ( $_old_files as $old_file ) {
+		$old_file = $to . $old_file;
+		if ( !file_exists($old_file) )
+			continue;
+		$wp_filesystem->delete($old_file, true);
+	}
+
 	// Force refresh of update information
 	delete_option('update_core');
 }